/*
  Copyright (C) 2007 Apple Inc.  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions
  are met:
  1. Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.
  2. Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
*/

/* The Great Computer Language Shootout
   http://shootout.alioth.debian.org/
   contributed by Isaac Gouy */

var PI = 3.141592653589793;
var SOLAR_MASS = 4 * PI * PI;
var DAYS_PER_YEAR = 365.24;

function Body(x,y,z,vx,vy,vz,mass){
  this.x = x;
  this.y = y;
  this.z = z;
  this.vx = vx;
  this.vy = vy;
  this.vz = vz;
  this.mass = mass;
}


Body.prototype.offsetMomentum = function(px,py,pz) {
  this.vx = -px / SOLAR_MASS;
  this.vy = -py / SOLAR_MASS;
  this.vz = -pz / SOLAR_MASS;
  return this;
}

function Jupiter(){
  return new Body(
    4.84143144246472090e+00,
      -1.16032004402742839e+00,
      -1.03622044471123109e-01,
    1.66007664274403694e-03 * DAYS_PER_YEAR,
    7.69901118419740425e-03 * DAYS_PER_YEAR,
      -6.90460016972063023e-05 * DAYS_PER_YEAR,
    9.54791938424326609e-04 * SOLAR_MASS
  );
}

function Saturn(){
  return new Body(
    8.34336671824457987e+00,
    4.12479856412430479e+00,
      -4.03523417114321381e-01,
      -2.76742510726862411e-03 * DAYS_PER_YEAR,
    4.99852801234917238e-03 * DAYS_PER_YEAR,
    2.30417297573763929e-05 * DAYS_PER_YEAR,
    2.85885980666130812e-04 * SOLAR_MASS
  );
}

function Uranus(){
  return new Body(
    1.28943695621391310e+01,
      -1.51111514016986312e+01,
      -2.23307578892655734e-01,
    2.96460137564761618e-03 * DAYS_PER_YEAR,
    2.37847173959480950e-03 * DAYS_PER_YEAR,
      -2.96589568540237556e-05 * DAYS_PER_YEAR,
    4.36624404335156298e-05 * SOLAR_MASS
  );
}

function Neptune(){
  return new Body(
    1.53796971148509165e+01,
      -2.59193146099879641e+01,
    1.79258772950371181e-01,
    2.68067772490389322e-03 * DAYS_PER_YEAR,
    1.62824170038242295e-03 * DAYS_PER_YEAR,
      -9.51592254519715870e-05 * DAYS_PER_YEAR,
    5.15138902046611451e-05 * SOLAR_MASS
  );
}

function Sun(){
  return new Body(0.0, 0.0, 0.0, 0.0, 0.0, 0.0, SOLAR_MASS);
}


function NBodySystem(bodies){
  this.bodies = bodies;
  var px = 0.0;
  var py = 0.0;
  var pz = 0.0;
  var size = this.bodies.length;
  for (var i=0; i<size; i++){
    var b = this.bodies[i];
    var m = b.mass;
    px += b.vx * m;
    py += b.vy * m;
    pz += b.vz * m;
  }
  this.bodies[0].offsetMomentum(px,py,pz);
}

NBodySystem.prototype.advance = function(dt){
  var dx, dy, dz, distance, mag;
  var size = this.bodies.length;

  for (var i=0; i<size; i++) {
    var bodyi = this.bodies[i];
    for (var j=i+1; j<size; j++) {
      var bodyj = this.bodies[j];
      dx = bodyi.x - bodyj.x;
      dy = bodyi.y - bodyj.y;
      dz = bodyi.z - bodyj.z;

      distance = Math.sqrt(dx*dx + dy*dy + dz*dz);
      mag = dt / (distance * distance * distance);

      bodyi.vx -= dx * bodyj.mass * mag;
      bodyi.vy -= dy * bodyj.mass * mag;
      bodyi.vz -= dz * bodyj.mass * mag;

      bodyj.vx += dx * bodyi.mass * mag;
      bodyj.vy += dy * bodyi.mass * mag;
      bodyj.vz += dz * bodyi.mass * mag;
    }
  }

  for (var i=0; i<size; i++) {
    var body = this.bodies[i];
    body.x += dt * body.vx;
    body.y += dt * body.vy;
    body.z += dt * body.vz;
  }
}

NBodySystem.prototype.energy = function(){
  var dx, dy, dz, distance;
  var e = 0.0;
  var size = this.bodies.length;

  for (var i=0; i<size; i++) {
    var bodyi = this.bodies[i];

    e += 0.5 * bodyi.mass *
      ( bodyi.vx * bodyi.vx
        + bodyi.vy * bodyi.vy
        + bodyi.vz * bodyi.vz );

    for (var j=i+1; j<size; j++) {
      var bodyj = this.bodies[j];
      dx = bodyi.x - bodyj.x;
      dy = bodyi.y - bodyj.y;
      dz = bodyi.z - bodyj.z;

      distance = Math.sqrt(dx*dx + dy*dy + dz*dz);
      e -= (bodyi.mass * bodyj.mass) / distance;
    }
  }
  return e;
}
function runAccessNBody() {
  var res;
  for ( var n = 3; n <= 24; n *= 2 ) {
    (function(){
      var bodies = new NBodySystem( Array(
        Sun(),Jupiter(),Saturn(),Uranus(),Neptune()
      ));
      var max = n * 100;
      res = bodies.energy();
      for (var i=0; i<max; i++){
        bodies.advance(0.01);
      }
      res = bodies.energy();
      trace(""+n+"="+res);
    })();
  }
  return res;
}

var _sunSpiderStartDate = new Date();
var res=runAccessNBody();
var totaltime=new Date()-_sunSpiderStartDate;

if (res-(-0.1690693)<0.00001)
  trace("Pass");
else
  trace("error nbody result expecting -0.1690693 got "+res);
